Miriam Davis
September 22, 2023
Appendicitis is widely known to be associated with colon cancer. Consider a 2020 meta-analysis finding that appendicitis increases the risk of colon cancer 10 fold. It is now standard practice for appendicitis patients to have preoperative imaging and intra-operative investigations to check for co-existing colon cancer.
But should all appendicitis patients older than 40 routinely receive colonoscopy post-appendectomy or after conservatively treated appendicitis? That’s where consensus ends.
The debate over colonoscopy after appendicitis has been ignited by a new study from French researchers in The Lancet’s EClinicalMedicine. The study, one of the largest and first nationwide of its kind, suggests that appendicitis may be an early consequence of the cancer rather than a contributing cause of it.
The French study looks at the time course of a colon cancer diagnosis during the first year after acute appendicitis. Comparing 230,000 appendicitis cases to 461,000 matched controls, the study found that colon cancer risk is highest – 8 times higher – during the first six months than during the second six months, or during the entire first year after acute appendicitis.
The risk is especially high for right-sided colon cancer. That risk is 13 times higher than controls, whereas left-sided colon cancer is only five times higher than controls.
“The most suitable” hypothesis emerging from these results, Lancet author Pablo Ortego-Deballon of Dijon University Hospital in France told Univadis, is that the growing colon tumour is a cause of acute appendicitis. Several possible mechanisms may be invoked, the most likely being that the growing tumour envelops the nearby appendix, exerting “an increase in the colon pressure patterns” and “leading to acute appendicitis,” he and co-authors write in their Lancet paper.
A proponent of routine colonoscopy (or CT colonography) for appendicitis patients older than 40 years of age is Shahab Hajibandeh of University Hospital of Wales, UK. The new Lancet study, he believes, adds to the imperative for definitive colon investigation.
“If a patient has acute appendicitis due to small, right-sided colon cancer,” the prevailing three steps in the “diagnostic pathway [are] likely to miss it,” he told Univadis. First, the “CT scan cannot identify small colonic lesions … Second, intraoperative assessment [by surgeons] … only identifies tumours that are large enough to be seen or to be felt … Third, normal histology of the appendix only provides information on the appendix and … does not exclude colon cancer.”
Hajibandeh, who was not involved in the Lancet study, points out, “We have previously shown that 1 out of 112 patients aged above 40, and 1 out of 66 patients aged above 50 with appendicitis, have co-existing, right-sided colon cancer.” He said that “despite the existence of convincing evidence, the current practice seems to be resistant to accepting the need for luminal investigation [ie, colonoscopy or CT colonography] following acute appendicitis in patients aged over 40.”
Lancet author Ortega-Deballon is more cautious. “I think we cannot recommend routine colonoscopy with our results because colonoscopy carries its own morbidity …. Moreover, the number of colonoscopies to perform would increase greatly,” leading to “economic impact” and a “challenge to healthcare systems to absorb such a demand,” he told Univadis. Instead, he argues for immune faeces assay as the least invasive approach and one that can be used for patients of any age. “In case of a positive result [on this type of assay], a colonoscopy could be warranted. But this needs to be confirmed in further studies,” he adds.
But Shahab Hajibandeh and colleagues assert that there is no evidence that faecal immunohistochemistry is sensitive enough to detect right-sided colon cancer. The resistance to colonoscopy, they write, comes especially from colorectal surgeons [concerned about] “increased workload for the already overwhelmed endoscopy service but also … a negative impact in terms of cost-effectiveness outcomes.”
Univadis.com published a clinical summary of this study on September 18.
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